I just saw the price of the Infinity lol I realized I need to go down a level
I'm hitting the same issue. I think we have maxed out our Edge Router (it get's insanely hot and utilization is often spiking to 70-90% with the QoS enabled.
I also so my 300 Mbps download speed drop to 100-160 Mbps (if I was lucky) and my 20 Mbps upload speed dropped to around 10-12 Mbps with the QoS enabled. I don't think it can handle the number of endpoints, QoS, and packet filtering we have on it. But at my other site, with same router but less people, endpoints etc they are just trucking along just fine. Of course there on a 100-150 Mbps download and 10-15 Mbps upload. But I think when everyone is on with every device, it's handling it fine.